중수로 압력관 재료의 조사 열화에 따른 인장거동 특성

안상복,김영석,김정규,An, Sang-Bok,Kim, Yeong-Seok,Kim, Jeong-Gyu 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.1

To investigate the degradation of mechanical properties induced mainly by neutron irradiation, the tensile tests were conducted from room temperature to 300\\`c using the irradiated and the unirradiated Zr-2.5Nb pressure tube materials. The irradiated longitudinal and transverse specimens were collected from the coolant inlet, middle, and outlet parts of M-11 tube which had been operated in Wolsung CANDU Unit-1 and exposed to different operating temperatures and irradiation fluences. The different tensile behavior was characterized not by the fluences of irradiation but by the tensile loading direction. The transverse specimen showed the higher strength and lower elongation than those of the longitudinal one. It was believed that these phenomena resulted from the microstructure anisotropy caused by the extrusion process. The increased strength hardening and decreased elongation embrittlement of the irradiated material were compard to those of the unirradiated one. While the tensile strength of the inlet was higher than that of the outlet, the elongation of the inlet was lower than that of outlet. Considering the operation condition, it was proposed that the operating temperature could be a more effective parameter than the irradiation fluence for long-time life. Through the TEM observation, it was found that while the a-type dislocation density was increased, the c-type dislocation was not changed in the irradiated. The fact that the higher dislocation density was sequentially distributed over the inlet, the middle, and the outlet parts was consistent with the distribution of the tensile strength.

CO₂ 레이저 빔 조사에 의한 프레스 금형재료의 표면경화 특성

양세영(Se-Young Yang),최성대(Seong-Dae Choi),최명수(Myeong-Soo Choi),전재목(Jae-Mok Jun) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.1

Recently, the technology of surface treatment is being more important which affects the material cost reduction and substitution to the expensive material. The material used for the mechanical processing should have not only high intensity, but also strength toughness, wear resistance and corrosion resistance. In order to increase the durability and have better quality of the parts using such kind of tooling material, various kinds of research of the surface hardening through many kinds of heat resources is being done and practically applied. In this study, the characteristics of hardening surface zone for high strength of the press die material through laser beam irradiation are researched. In this study, it is experimentally observed by the status of the surface morphology, tensile strength, the hardness distribution of the base metal and wear condition by the surface hardness pattern by the laser beam based on the process parameters of CO₂ laser by using SM45C and STD11 used for press tool. Through this research, the characteristics of surface hardened zone for high strength of the thin metal by laser beam irradiation is done.

월성 1호기 중수로 압력관의 조사후 인장거동 특성

안상복(Sang-Bok AHN),오동준(Dong-Jun OH),권상철(Sang-Chul Kwon),김영석(Young-Suk KIM),김정규(Jung-Kyu KIM) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3

The tensile test of irradiated and un irradiated Zr-2.5Nb CANDU pressure tube materials in the temperature range of room to 300℃ have been conducted to investigate the degradations of mechanical properties induced mainly by neutron irradiations. The irradiated longitudinal and transverse specimens which had a different operation temperatures and irradiation amounts are fabricated at coolant inlet, middle, and outlet part rings from M-11 tube operated in Wolsung Unit-1. A different tensile behaviors are showed with the specimen directions in the irradiated and un irradiated ones. The transverse have higher strength and lower elongation than the longitudinal specimens. It is believed to the effect of the microstructure anisotropy caused by extrusion fabrication process. The increased strength hardening and the decreased elongation embrittlement are showed in the irradiated ones compared to those of the un irradiated. The strength and elongation in the inlet part are higher and smaller compared to the outlet part. Specially in the same ring, the upper postion specimen have higher strength than the lower. Considering the operation temperature and irradiation amount distributions in tube, it is proposed that the irradiation temperature in tensile properties degradation can be more sensitive factor.

멀티스케일 모델링을 이용한 압력용기강의 조사손상 정량예측

이경근,권준현,Lee, Gyeong-Geun,Kwon, Junhyun 한국압력기기공학회 2014 한국압력기기공학회 논문집 Vol.10 No.1

In this work, an integrated model including molecular dynamics and chemical rate theory was implemented to calculate the growth of point defect clusters(PDC) and copper-rich precipitates(CRP) which could change the mechanical properties of reactor pressure vessel(RPV) steels in a nuclear power plant. A number of time-dependent differential equations were established and numerically integrated to estimate the evolution of irradiation defects. The calculation showed that the concentration of the vacancies was higher than that of the self-interstitial atoms. The higher concentration of vacancies induced a formation of the CRPs in the later stage. The size of the CRPs was used to estimate the mechanical property changes in RPV steels, as is the same case with the PDCs. The calculation results were compared with the measured values of yield strength change and Charpy V-notch transition temperature shift, which were obtained from the surveillance test data of Korean light water reactors(LWRs). The estimated values were in fair agreement with the experimental results in spite of the uncertainty of the modeling parameters.

Nd:YAG 레이저 충격 피닝에 의한 프레스 금형재료의 표면경화 특성

전재목(Jae-Mok Jeon),양세영(Se-Young Yang) 산업기술교육훈련학회 2013 산업기술연구논문지 (JITR) Vol.18 No.2

The development of the surface treatment technology is extremely critical with the recent trend of the various new materials such as composites, alloys with complicated structures. Wear resistance is the most important aspect in die and mold industry which enables the mass production with proper quality control. Laser shock peening is a new technology of the surface treatment which is supposed to increase the durability and have better quality of the parts using such kind of tooling material, various kinds of research of the surface hardening through many kinds of heat resources is being done and practically applied. In this study, it is experimentally observed by the status of the surface morphology, tensile strength, the hardness distribution of the base metal and wear condition by the surface hardness pattern by the laser beam based on the process parameters of Nd:YAG laser shock peening by using press die materials. Through this research, the characteristics of surface hardened zone for high strength of the thin metal by laser beam irradiation is done. The effect on the wear resistance and improvement of the mechanical properties is identified in the application to the materials for the press die.

자외선 조사된 HTV 실리콘 고무의 표면열화 분석

연복희,이태호,허창수,이종한 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.5

In this paper we have investigated the surface degradation by ultraviolet-irradiation in high-temperature vulcanized silicone rubber. Through the measurement of surface potential decay by corona-charging and of contact angle it is found that the change of surface electrostatic properties and the decrease of contact angle under UV-radiation. For the changes in micro-morphological and chemical structure of the UV-treated silicone rubber we utilized several analytical techniques such as SEM, ATR-FTIR,XPS. From this study it is shown that the chemical reactions(scissoring of side chain(S-$CH_3$) cross-linking and branching) occur on the surface of silicone rubber during the UV-irradiation. Also we obtained the results of the loss of low molecular weight chain by cross-linking and oxidation reaction.

레이저 빔에 의한 박판금속의 강화특성

양세영,최성대,김기만,전재목,공병채,Yang, Se-Young,Choi, Seong-Dae,Kim, Gi-Man,Jun, Jea-Mok,Gong, Byeong-Chae 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.2

The general way to process the surface by means of the laser was heat treatment for strengthening the surface hardness. They have used the laser for changing the property of the surface, especially for metal. Generally, it is recent increasing tendency to use the thin plate panel for making things smaller and lightweight. However, thin plate should be strengthened or let the thin plate panel have moment of inertia by means of engraving the groove or wave on them for lightweight and strengthening. Therefore it is expected that the thin plate panel can be harder and more stable through processing the metal surface by laser beam irradiation and the hardness of thin plate possibly can be also changed how many parts of them are harden. Through this research, it can be grasped how the hardness and mechanical characteristic changes according to width and depth of groove by laser affect the max stress by the ratio of $A_H/A_T$ (hardening area/total area) and characteristic of displacement and structural characteristic for making the thin plate harder by the strengthening metal surface of thin plate by laser through the experiment and analysis of FEA can be presented.

레이저 빔에 의한 박판금속의 강화특성

양세영(Se-Young Yang),최성대(Seong-Dae Choi),김기만(Gi-Man Kim),전재목(Jea-Mok Jun),공병채(Byeong-Chae Gong) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.2

The general way to process the surface by means of the laser was heat treatment for strengthening the surface hardness. They have used the laser for changing the property of the surface, especially for metal. Generally, it is recent increasing tendency to use the thin plate panel for making things smaller and lightweight. However, thin plate should be strengthened or let the thin plate panel have moment of inertia by means of engraving the groove or wave on them for lightweight and strengthening. Therefore it is expected that the thin plate panel can be harder and more stable through processing the metal surface by laser beam irradiation and the hardness of thin plate possibly can be also changed how many parts of them are harden. Through this research, it can be grasped how the hardness and mechanical characteristic changes according to width and depth of groove by laser affect the max stress by the ratio of AH/AT (hardening area/total area) and characteristic of displacement and structural characteristic for making the thin plate harder by the strengthening metal surface of thin plate by laser through the experiment and analysis of FEA can be presented.

동맥경화로 인한 사망과 식이섭취유형의 변화

김영옥,윤석권 생활과학연구소 2005 생활과학연구 Vol.10 No.-

The purpose of this study were to identify dietary pattern in relation to artherosclerosis among Korean. The relationship was investigated based on longitudinal observation of diet and artherosclerosis prevalence during 1970-2000. The observed year of artherosclerosis prevalence had been matched with 10 years interval after the year of food consumption. Artherosclerosis prevalence was studied based on cause of death during 1980-2000. Food consumption was studied using the Korean National Health and Nutrition Survey during 1970-1990. As a result artherosclerosis prevalence increased with increasing consumption of meat, fish, egg, fruit up to the certain level of consumption. However, the relationship disappear when the prevalence had reached the higher level of prevalence. It may imply that other health related behavioral factors than dietary factor had influenced more on artherosclerosis incidence when the rate of incidence had reached higher level.